(a) Field of the Invention
The present invention relates to an in-band full duplex transceiver.
(b) Description of the Related Art
A current wireless communication system uses a half duplex method. The half duplex method transmits or receives signals by dividing time or frequency so orthogonality between transmitting and receiving may be maintained. However, the half duplex method wastes resources (time or frequency), has a problem in a multi-hop relay among mobile small cells, and requires additional overhead to solve a hidden node problem.
The in-band full duplex method is suggested as a solution for solving non-efficiency of the half duplex method. The in-band full duplex method represents a method for allowing simultaneous in-band transmitting/receiving. The in-band full duplex method may increase link capacity by twice to a maximum in a theoretical manner so it is an essential technique for achieving 1000 times the traffic capacity required by the 5G mobile communication.
However, the in-band full duplex method allows a self-transmitting signal to be input to a receiver so the self-transmitting signal functions as a self-interference signal very strongly compared to a valid received signal, which is a drawback. To cancel the self-interference (called self-interference cancellation (SIC)), an antenna region SIC technique for physically separating a transmitting antenna from a receiving antenna with a large distance therebetween has been provided. A technique for reducing a self-interference level by using the antenna region SIC technique, and canceling remaining self-interference in a digital region, is called an interference cancellation system (ICS) technique. A problem of the ICS technique is that it is impossible to be applied to a small device because of the physical separation between the transmitting and receiving antennas.
An electrical balance duplex (EBD) is one of SIC techniques in the in-band full duplex method, but the EBD technique deteriorates SIC performance or destabilizes it as the system bandwidth becomes wider. That is, the existing EBD technique has a problem in that an SIC gain is great for a specific frequency bandwidth and it becomes less in other frequency bandwidths.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.